Used Super Duper to make a clone of my Lion OS on my 2011 MBP. I used a WD My Passport. If you decide to use SD, make sure you select," Erase HD, etc" in General Settings. After it was complete I held Option key on start and booted from the My Passport. It worked perfectly and re-booted with the clone. Of course, it was slower than my SSD in the hard drive, but it is nice to know that I have a working copy with me when I travel.